--- linux-2.6.19/include/linux/swap.h
+++ linux-2.6.19/include/linux/swap.h
@@ -123,6 +123,12 @@
 	SWP_SCANNING	= (1 << 8),	/* refcount in scan_swap_map */
 };
 
+enum swap_event {
+	SWAP_EVENT_SWAPON,
+	SWAP_EVENT_SWAPOFF,
+	SWAP_EVENT_SLOT_FREE,
+};
+
 #define SWAP_CLUSTER_MAX 32
 
 #define SWAP_MAP_MAX	0x7fff
@@ -138,6 +144,7 @@
 	struct block_device *bdev;
 	struct list_head extent_list;
 	struct swap_extent *curr_swap_extent;
+	struct atomic_notifier_head slot_free_notify_list;
 	unsigned old_block_size;
 	unsigned short * swap_map;
 	unsigned int lowest_bit;
@@ -253,6 +260,10 @@
 extern struct swap_info_struct *get_swap_info_struct(unsigned);
 extern int can_share_swap_page(struct page *);
 extern int remove_exclusive_swap_page(struct page *);
+extern int register_swap_event_notifier(struct notifier_block *nb,
+			enum swap_event event, unsigned long val);
+extern int unregister_swap_event_notifier(struct notifier_block *nb,
+			enum swap_event event, unsigned long val);
 struct backing_dev_info;
 
 extern spinlock_t swap_lock;
--- linux-2.6.19/mm/swapfile.c
+++ linux-2.6.19/mm/swapfile.c
@@ -47,6 +47,8 @@
 static struct swap_info_struct swap_info[MAX_SWAPFILES];
 
 static DEFINE_MUTEX(swapon_mutex);
+static BLOCKING_NOTIFIER_HEAD(swapon_notify_list);
+static BLOCKING_NOTIFIER_HEAD(swapoff_notify_list);
 
 /*
  * We need this because the bdev->unplug_fn can sleep and we cannot
@@ -284,6 +286,9 @@
 				swap_list.next = p - swap_info;
 			nr_swap_pages++;
 			p->inuse_pages--;
+			atomic_notifier_call_chain(&p->slot_free_notify_list,
+						offset, p->swap_file);
+
 		}
 	}
 	return count;
@@ -1243,6 +1248,7 @@
 	p->swap_map = NULL;
 	p->flags = 0;
 	spin_unlock(&swap_lock);
+	blocking_notifier_call_chain(&swapoff_notify_list, type, swap_file);
 	mutex_unlock(&swapon_mutex);
 	vfree(swap_map);
 	inode = mapping->host;
@@ -1615,7 +1621,9 @@
 	} else {
 		swap_info[prev].next = p - swap_info;
 	}
+	ATOMIC_INIT_NOTIFIER_HEAD(&p->slot_free_notify_list);
 	spin_unlock(&swap_lock);
+	blocking_notifier_call_chain(&swapon_notify_list, type, swap_file);
 	mutex_unlock(&swapon_mutex);
 	error = 0;
 	goto out;
@@ -1751,3 +1759,61 @@
 	spin_unlock(&swap_lock);
 	return ret;
 }
+
+int register_swap_event_notifier(struct notifier_block *nb,
+				enum swap_event event, unsigned long val)
+{
+	switch (event) {
+	case SWAP_EVENT_SWAPON:
+		return blocking_notifier_chain_register(
+					&swapon_notify_list, nb);
+	case SWAP_EVENT_SWAPOFF:
+		return blocking_notifier_chain_register(
+					&swapoff_notify_list, nb);
+	case SWAP_EVENT_SLOT_FREE:
+		{
+		struct swap_info_struct *sis;
+
+		if (val > nr_swapfiles)
+			goto out;
+		sis = get_swap_info_struct(val);
+		return atomic_notifier_chain_register(
+				&sis->slot_free_notify_list, nb);
+		}
+	default:
+		printk(KERN_ERR "Invalid swap event: %d\n", event);
+	};
+
+out:
+	return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(register_swap_event_notifier);
+
+int unregister_swap_event_notifier(struct notifier_block *nb,
+				enum swap_event event, unsigned long val)
+{
+	switch (event) {
+	case SWAP_EVENT_SWAPON:
+		return blocking_notifier_chain_unregister(
+					&swapon_notify_list, nb);
+	case SWAP_EVENT_SWAPOFF:
+		return blocking_notifier_chain_unregister(
+					&swapoff_notify_list, nb);
+	case SWAP_EVENT_SLOT_FREE:
+		{
+		struct swap_info_struct *sis;
+
+		if (val > nr_swapfiles)
+			goto out;
+		sis = get_swap_info_struct(val);
+		return atomic_notifier_chain_unregister(
+				&sis->slot_free_notify_list, nb);
+		}
+	default:
+		printk(KERN_ERR "Invalid swap event: %d\n", event);
+	};
+
+out:
+	return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(unregister_swap_event_notifier);